The present application relates to a fine particle detector and a light emitting apparatus, and more particularly, to a fine particle detector or the like that optically analyzes the characteristics of fine particles such as cells or microbeads.
A fine particle detector of the related art emits light (laser) to fine particles flowing in a flow cell or in a flow channel formed on a microchip, detects scattered light from the fine particles or fluorescence generated from the fine particles themselves or fluorescent material marked on the fine particles, and measures the optical characteristics of the fine particles. In addition, this fine particle detector separately collects the population determined to meet predetermined conditions from the fine particles, as a result of the measurement of optical characteristics. Of such fine particle detectors, the apparatus that measures the optical characteristics of cells as fine particles or separately collects the cell population that meets predetermined conditions is particularly called a flow cytometer, cell sorter, etc.
For example, Japanese Unexamined Patent Application Publication No. 2007-46947 discloses the flow cytometer that including a plurality of light sources that emits a plurality of excitation light beams each having a different wavelength and a different phase at predetermined time intervals and including a waveguide member that guides the plurality of excitation light beams to the same entrance optical path and focuses the plurality of light beams on dyed particles. This flow cytometer includes a plurality of light sources that emit a plurality of excitation light beams each having a different wavelength, a waveguide member that guides the plurality of excitation light beams to the same entrance optical path and focuses the plurality of excitation light beams on dyed particles, and a plurality of fluorescence detectors that detect fluorescence generated from the dyed particles excited by the plurality of excitation light beams and output fluorescence signals (see claims 1 and 3 and FIGS. 1 and 3 in the Japanese Unexamined Patent Application Publication No. 2007-46947).
In the fine particle detector of the related art, as shown in FIG. 6, a laser L is focused on a sample flow S by a focusing lens 103, and fine particles P flow through the sample flow S so as to cross the spot of the laser L focused. At this time, the strength distribution in the laser spot becomes a Gaussian distribution, in which the strength is large in the center of the laser spot and reduces significantly in the periphery. FIG. 7 shows an example of the strength distribution in a laser spot for the fine particle detector of the related art. If there are variations in the flow positions of a fine particle P in the sample flow S, the effective strength of the laser emitted differs between the fine particle P passing the center of the laser spot and the fine particle P passing the peripheral of the laser spot, thereby introducing error in the signal strength obtained.